1. Field of the Invention
The present invention relates to spinning preparations and processes for the melt spinning of synthetic fibers.
2. Description of the Related Art
In the melt spinning of synthetic fibers and their further processing into textile or industrial yarns, the multifilament yarns are wound without twisting onto spinning bobbins. The individual capillaries are in the form of bundles of parallel filaments, being held together solely by the more or less clearly pronounced adhesion effect of the spinning preparation. In the subsequent drawing process, the yarns are normally given a protective twist of a few turns per meter. However, this protective twist is not sufficient for many subsequent processing operations. Accordingly, the filaments either have to be twisted or protected by coating with a film of size in a separate process step. Both twisting and also sizing are expensive additional process steps. Accordingly, investigations have long been made to find alternatives for improving the inter-filament cohesion of the yarns to such an extent as to make these process steps superfluous.
The spinning preparations used in the past contain as filament cohesion promoters such additives as sarcosides or polymers of relatively high viscosity, such as polyisobutylene. Depending on the concentration in which they are used, compounds such as these are capable of improving the cohesion-promoting effect of spinning preparations by increasing the adhesion forces between the individual capillaries. However, the cohesion effect obtained in this way is only temporary because the additives in question are washed out again during the first wet process, for example in the dyeing operation. Another disadvantage attending many of these cohesion promoters lies in their inadequate thermal stability. This seriously restricts their use for spinning preparations which are intended for texturing or for industrial yarns which have to be subjected to high-temperature drawing.